A Structure and Design Method of Magnetic Integration for Wide-Input-Voltage High-order Resonant Dual Active Bridge Converter

In this article, a magnetic integration structure and its parameter design methodology for high-order CLLLC resonant converter are proposed. First, the topology of the CLLLC converter is established through theoretical analysis of the resonant network. To ensure maximum power output and reduce harmonic content, the parameters of the magnetizing inductance, primary resonant inductance, and secondary resonant inductance are systematically designed. To reduce the number, volume, and loss of magnetic cores while simultaneously enhancing power density, the primary and secondary resonant inductances are implemented as the leakage inductance of the transformer. To achieve the global optimum of integrated core volume and loss, a systematic parameter optimization process is proposed. In this process, the number of primary winding turns and the number of primary printed circuit board (PCB) are set as free design variables. Based on these two variables, all related parameters of the magnetic core and PCB windings can be fully derived. Multiple sets of volume-loss combinations for the integrated core are generated through the variation of these free parameters. The optimal solution is then selected from these sets, ultimately achieving the comprehensive minimization of the integrated core's volume and loss. To validate the effectiveness of the proposed method, it is applied to a 1.2kW high-order CLLLC resonant converter experimental prototype with a switching frequency of 125kHz, an input voltage range of 150-300V, and an output voltage of 200V. The experimental results fully verify the correctness of the converter's operating mode, the soft-switching performance of the switches, and the high-efficiency characteristics of the system, thereby demonstrating the effectiveness of the proposed magnetic integration structure and optimization methodology.